This invention relates to an electrohydraulic valve, and in particular, to a solenoid-operated, poppet-type, four-way, four-position valve.
Conventional pressure-compensated flow control valves, such as described in U.S. Pat. No. 3,587,630, have spool-type directional control valves in series with load check valves. The spool valve elements perform the primary metering function while the poppets perform only secondary sealing or load checking functions. Because spool-type valves are susceptible to contaminants in the hydraulic fluid, it has been proposed to control double-acting hydraulic cylinders via on-off type poppet valves controlled by solenoid-operated pilot valves. For example, a four-function (off, extend, retract and float) valve is described in U.S. application, Ser. No. 364,373, filed Apr. 1, 1982, now U.S. Pat. No. 4,437,385. However, this valve requires four separate pilot controlling soleniods. An electrohydraulic valve with only two solenoids is described in U.S. application, Ser. No. 416,836, filed Sept. 13, 1982, now U.S. Pat. No. 4,461,314. However, this valve lacks a "float" function and thus, does not have full four-function capability.